This invention relates to an aircraft with an emergency landing system, having a longitudinal axis running through the center of gravity and a vertical axis essentially perpendicular thereto, which can be activated by a start signal from a trigger unit actuatable by operating parameters of the aircraft. The emergency landing system includes a paraglider for the emergency landing phase of the aircraft, and the trigger unit is adjusted so that a drag or a brake and attitude positioning parachute which is attached to the aircraft is ejected when the start signal appears.
An aircraft having the above-described combination of features represents prior art developed by the applicant, publication of which is not known. It is, however, generally known from the prior art to pull an emergency parachute from its storage position to an operating position by use of a small drag parachute.
An aircraft having an emergency landing system is known from German document DE 42 39 638 A1. The emergency landing system can be activated by a start signal triggered by operating parameters of the aircraft, and includes a drag parachute, attached to the aircraft by drag lines, for reducing the speed. The drag parachute, at the same time, also causes the aircraft to assume an oblique position which inclines the tail of the aircraft downward. In this flight phase, a second parachute for the emergency landing is automatically opened. During the subsequent hard landing, the tail of the aircraft is deformed, whereas the dimensionally rigid cabin remains essentially unchanged.
German documents DE 199 34 210 A1 and DE 25 03 322 A1 describe emergency landing systems for aircraft in which paragliders or parafoils are provided for emergency landing phases. In each case, the flight position of the aircraft in the emergency landing phase undergoes little or no change compared to the normal flight phase.
One object of the present invention is to enable an aircraft, operating at flight speeds in the range of 200 m/sec and higher, to land safely, i.e., without damage, by use of a paraglider, specifically in the case of an emergency situation such as engine failure. One aim is to minimize the structural complexity of such an emergency landing system, and to provide a system which guarantees high reliability. A further aim is to ensure that the installation space necessary for the emergency landing system, which is not insignificant because of the paraglider required for the emergency landing phase, is kept as small as possible, since the installation space in aircraft for which such an emergency landing system is considered, principally unmanned military aircraft, is very limited. Lastly, consideration should be made for the fact that the aircraft to be landed typically has a high speed, in the range of over 200 m/sec, when an emergency such as engine failure occurs. The aircraft therefore must be decelerated from a cruise motion to a descent motion before the paraglider for the emergency landing phase can be folded out, since paragliders can be opened only below speeds in the range of 50 m/sec.
The above-referenced requirements are met by an aircraft according to the invention.
In one embodiment of the invention, a release unit, by way of extension lines, pulls out an attitude positioning parachute from a storage position into a braking position when the flight speed drops below a predetermined first threshold speed. A pair of first suspension lines for the attitude positioning parachute is mounted on the aircraft behind, relative to the longitudinal axis, the center of gravity thereof, and a pair of second suspension lines is attached in front of the center of gravity of the aircraft. A positioning device causes the braking force from the attitude positioning parachute acting on the first suspension lines to be partially transferred to the second suspension lines when the flight speed drops below a second threshold speed, and the aircraft swivels with respect to its direction of motion. An unfolding device for the paraglider unfolds the latter as soon as the aircraft swivels in such a way that the vertical axis essentially corresponds to the direction of pull from the attitude positioning parachute, and the speed of the aircraft drops below a predetermined maximum paraglider speed.
In another embodiment of the invention, a brake and attitude positioning parachute is attached to the aircraft, and a pair of first suspension lines for a braking and attitude positioning parachute is mounted on the aircraft behind, relative to the longitudinal axis, the center of gravity thereof. A pair of second suspension lines is attached in front of the center of gravity of the aircraft. A positioning device causes the braking force from the braking and attitude positioning parachute acting on the first suspension lines to be partially transferred to the second suspension lines when the flight speed drops below a predetermined second threshold speed, and the aircraft swivels with respect to its direction of motion. An unfolding device for the paraglider unfolds the paraglider as soon as the aircraft swivels in such a way that the vertical axis essentially corresponds to the direction of pull from the braking and attitude positioning parachute, and the speed of the aircraft drops below a predetermined maximum paraglider speed.
One advantage of an aircraft having an emergency system as mentioned is that, to decelerate the aircraft from a high initial flight speed to a flight and descent speed that is suitable for a paraglider, besides the typically used auxiliary parachute (referred to here as “drag parachute”), only a brake parachute is necessary. The brake parachute decelerates the aircraft, and also causes the aircraft to swivel with respect to the direction of pull from this parachute as the result of appropriate attachment of the suspension lines, and is therefore referred to as an attitude positioning parachute. Thus, after an auxiliary parachute has reduced the initial flight speed and has pulled out the attitude positioning parachute from its storage position, in a first phase in the normal flight position of the aircraft, in which the direction of motion coincides with the longitudinal axis of the aircraft, the aircraft is decelerated by the attitude positioning parachute to a speed that permits the aircraft to swivel. In the second phase, appropriate control of the introduction of force to the aircraft by the attitude positioning parachute causes the aircraft to swivel in such a way that the vertical axis essentially corresponds to the direction of pull from the attitude positioning parachute, and the aircraft therefore goes into a descent. Only in a third phase is the paraglider pulled upward from the aircraft and used for a descent and a glide landing. A landing gear which may be present is extended, and in this manner a landing gear landing is achieved.
According to other claimed subject matter, a separate drag parachute is omitted. The attitude positioning parachute is used for both deceleration and attitude positioning, for which reason this parachute is referred to below as a brake and attitude positioning parachute. In one advantageous embodiment, in a first phase after ejection, the brake and attitude positioning parachute is only partially unfolded; i.e., it has a smaller diameter compared to the fully unfolded state. Only when a predetermined threshold speed is reached is the brake and attitude positioning parachute fully unfolded, by means of a release device such as a pyrotechnic cutter, for example. After further deceleration, the aircraft ultimately swivels.
In one preferred embodiment of the invention, which meets the requirement for structural simplicity, the positioning device for the attitude positioning parachute or for the brake and attitude positioning parachute is designed to include a clamping device in which the first suspension lines may be fixed in position on a portion of its total length. The entire length of the first suspension lines may be released after the speed drops below the second threshold speed, and the length of the second suspension lines is coordinated so that release of the clamping device causes tensile force from the attitude positioning parachute to be applied to the second suspension lines. This design incorporates not only structural simplicity, an extremely small space requirement, and low cost, but also maximum operational safety.
It is also possible to transfer the braking force of the attitude positioning parachute or the brake and attitude positioning parachute from the first pair of suspension lines to the second pair of suspension lines for swiveling the aircraft in a stepwise manner in order to maintain the most stable aircraft flow conditions possible. Starting from a relatively high speed upon initial swiveling of the aircraft, only a slight degree of swivel is initiated which corresponds to the typical aircraft stabilizer settings. Only after further deceleration is the swiveling then increased by steps until the vertical axis of the aircraft essentially corresponds to the direction of pull from the attitude positioning parachute.
Lastly, in a further embodiment of the invention, it is advantageous to also design the release device for pulling out the attitude positioning parachute from its storage position into a braking position by use of a clamping device for the suspension lines to which the extension lines are attached. The length of the extension lines is coordinated with a clamping length of the suspension lines such that, when the clamping device is opened, braking tension from the drag parachute is transferred from the suspension lines to the extension lines, thereby unfolding the attitude positioning parachute.
Various embodiments of the invention are described with reference to the appended drawings.